Building the most accurate DIY CNC lathe in the world [video]

Also of interest if you enjoy precision engineering: https://www.youtube.com/watch?v=sFrVdoOhu1Q&pp=ygUdZGFuIGdlb...

For a more rough and ready, but quite entertaining, version of the DIY CNC (mill however) build there's the sage of Not An Engineer's build of a DIY CNC mill.

https://www.youtube.com/watch?v=uallSKJGoug&list=PL3NwjxPeyb...

I've been following Cylo's Garage for a while. I'm excited to see where he goes. Reminds me of Applied Science meets Tom Lipton, Robin Renzetti, or Dan Gelbart.

Cyrus(creator of Cylo's Garage) written a paper on the diamond lathe design:

https://drive.google.com/file/d/178KoqYAQUScSW27opubo9K794Pe...

Another awesome video on precision engineering resources in the same channel:

https://m.youtube.com/watch?v=FM9X_gjnleY

Worth noting that the lathe project itself is on indefinite hiatus right now as I understand it, so don't hold your breath waiting to see finished results.

People interested in this might also appreciate this small channel: a no-holds-barred 5 axis machine with expected sub-micron precision. I've learned a lot about what kind of components are available when budget is not an issue (I'll bet this machine will cost 100k by the time it's done). https://www.youtube.com/@kasramehraky9283

I love that channel so much

Most do not understand how difficult these machines are to handle, but there are some completed specialty CNC builds around.

"High precision air bearing CNC lathe and grinder" (Dan Gelbart)

https://www.youtube.com/watch?v=sFrVdoOhu1Q

Cylo's Garage spent a lot of time exploring these designs. =3

Not CNC, but I am addicted to the Cutting Edge Engineering channel:

https://www.youtube.com/channel/UC2wdo5vU7bPBNzyC2nnwmNQ

Normally I would assume that a YouTuber claiming to have built a more accurate DIY CNC lathe than Dan Gelbart's was full of shit, especially if he didn't mention Gelbart in the title. But Cylo's Garage is an exception. His objective is diamond-turning optics. So he does need tighter precision than Gelbart's 1μm, and he's been working toward achieving it in an astounding fashion for years—inspired, he tells us in the video, by Gelbart.

This video, though? You know how people say "this meeting could have been an email"? This video could have been a web page. Or an email. It's just a set of slides with a voiceover. Save yourself the time and just read the subtitles:

    yt-dlp --write-info-json --write-sub --write-auto-sub --sub-lang en --restrict-filenames https://www.youtube.com/watch?v=vEr2CJruwEM

For reading the subtitles file Building_the_most_accurate_DIY_CNC_lathe_in_the_world-[vEr2CJruwEM].en.vtt, http://canonical.org/~kragen/sw/dev3/devtt.py may be useful.

For folks who are not familiar w/ machine shops, the lathe is a fundamental tool in a shop, and is the only tool in a shop which can replicate itself --- there is even a book series which uses this conceit, the "Gingery Books":

https://gingerybookstore.com/

where Vol. 1 has one setting up an aluminum casting foundry in one's backyard, and Vol. 2 has one using it to make a lathe which is then used to either improve itself or make a better lathe, then one uses it to make the balance of the tools in a machine shop.

Results of Diamond lathe testing photage: https://m.youtube.com/watch?v=PuSHpD7hiQ0

A lathe can't actually replicate itself completely. Specifically, a lathe can only make ways smaller than its own cross slide's stroke. It would also be impossible to make a typical lathe bed on a lathe, though you theoretically could design an unconventional lathe bed that is possible to make on a lathe, even if grossly impractical.

The real starting point for machine precision is rubbing 3 granite plates together.

Lathes can certainly make cylinders, and a tube-based lathe bed is not a stretch.

A lathe can't replicate its own assembly, of course. It can't seat the spindle in the constraint bearings, for instance.

A CNC (without the word lathe) can make most of itself, and possible all. Nope: certainly all, if two of its dimensions fit within its work volume.

Those are the kind of CNC kept in isolated rooms, and covered in gold foil to reflect heat. No humans allowed during the measurement cycle.

It's so cool to see Cylo get posted here. I remember finding his channel via an air bearing video years ago and being so impressed at what a (then) kid was doing, cool to see him still doing stuff and getting recognized for it. For anyone enjoying this Dan Gelberts video on his lathe, which I think inspired this, is worth watching. Robin Renzetti also does cool precision focused stuff but I don't know if he does Youtube much anymore.

But it can't make cylinders as long as its own guide ways.

I can't believe this kid can afford an incredible amount of expensive tools.. daddys money?

Lathes can make cylinders, but not of unlimited length in one setup so they lose some accuracy making cylinders longer than their carriage travel. And their beds are by necessity longer than their carriage travel, since the carriage rides along the bed and isn't infinitely thin. They also can't make things like motor stator laminations, and you definitely need a motor for a replica of a motorized lathe. So lathes can't replicate themselves exactly.

Milling machines are also just lathes with a different orientation, an extra travel axis, and a motor optimized for higher speeds & lower torques, it's possible (and reasonably common) to use a mill like a lathe or a lathe like a mill in many cases. So "only machine" part is also a stretch.

Yeah, that's a different book, _Foundations of Mechanical Accuracy_:

https://mitpress.mit.edu/9780262130806/foundations-of-mechan...

> and is the only tool in a shop which can replicate itself

The real quote is a lathe can build any tool in a machine shop, - including itself. The books your mention describe how to build a lathe with the lathe you are building. (they assume surface plates that the other reply mentioned, but that too is something you can create)

most are sold out any kinks to ebooks sold?

It would be interesting to see someone use basic hand tools to build up the evolutionary steps towards high end machining or manufacturing machines of all kinds. Sort of a playbook to restart civilization.

How To Make Everything on YouTube is along those lines

https://youtube.com/@htme

You can buy the full series. Or check the likes of amazon. The books were first written in 1980, so they are fairly widespread. You can find plenty of youtube videos of people trying to make them, and once in a while forums dedicated to people making them (and suggested upgrades). They are not the best machine cools you can get/make, but they are serious tools and better than most DIY attempts (though the video here is better than most DIY attempts I've seen)

make me a truly flat surface

You can see a guy following Dave Gingery's instructions to make a lathe bed here [1]

And as you say, a granite surface plate is needed. Of course, Gingery's books only claimed to set up a metalworking shop starting "from scrap" and "simple hand methods" and that "it isn’t long before the developing machines are doing much of the work to produce their own parts" [2]

Of course, to truly make a lathe from scratch, you must first create the universe.

[1] https://www.youtube.com/watch?v=zPGZg45dGXA [2] https://gingerybookstore.com/MetalWorkingShopFromScrapSeries...

s/conceit/concept/

It's kind of sad how much knowledge is hidden inside companies.

(I'm assuming something like this was achieved decades ago in certain companies.)

Related to the Moore's work, I also enjoyed Engineering reminescences[0] as a historical account how people figured out ways to make accurate things in metal, more than a hundred years ago.

0: https://www.gutenberg.org/ebooks/72043

Does anybody actually use the three plate method with granite? It was originally done with cast iron, and I thought cast iron was still the standard material. The plates are covered with dye and rubbed together to find the high points, which are then scraped off, instead of being removed by the rubbing directly.

Granite is a common material for modern surface plates (and a good one because it doesn't rust and doesn't raise burrs if it's chipped), but I believe these are still made using cast iron reference plates.

Sadly no episode this week as Kurtis' father died unexpectedly.

Before I started watching CEE, I watched Abom79

https://www.youtube.com/@Abom79/videos

He has a bunch of lathe video's too.

From what I understand the three plate method is when you are going from 0 to flat as the errors are averaged out.

Doing the "covered with dye and rubbed together to find the high points, which are then scraped off" thing is only if you already have a flat reference surface as you wouldn't have a way to know if the thing you're trying to make flat is really flat.

The real question is how do you get the first flat reference surface when all you have are a few somewhat flat things?

Why cast such negative aspersions on a stranger doing good work?

If you are smart and patient you can find good used machine tools for very cheap (relative to their new cost). I would guess that buying a new Honda Civic costs more than what this person has in their shop. And if you bother to watch the video, you see at the end that he takes what he makes home to a different shop, implying that this is a shared or borrowed set of machine tools. Buying a bunch of tools that will hold their value while producing more value is not a sign of being reckless with someone else’s money.

Would you make such judgements about every Honda owner for spending a five figure sum?

Also for those who aren't familiar, there's also "hand scraping" for flatness which is more common and used for things like refreshing the "ways" (ie precision linear bearings) on a lathe or other precision machine tool.

This is done like the "dye / rub / scrape" method described above, which I believe is still used as it's superior to grinding for these applications.

See video below for the process: https://www.youtube.com/watch?v=T7w84CrBEE8

> The real question is how do you get the first flat reference surface when all you have are a few somewhat flat things?

my understanding is the threeplate method allows you to build the reference plate in the first place.

if the purpose is to bootstrap, you could also use something like a leather belt drive off a central shaft, which would require different power sources but ones that a higher percentage of could be made with a lathe

The three plates is the foundationiof accuracy but no tools are needed to create them. you need a lathe to create a lathe - but a lathe can build itself as by the time you need a lathe in construction you already have enough of a lathe built for that next step.

Hand scraping is done, but for ultimate flat you need to lap three plates not hand scrape. Hand scrapping is not as flat - but the average is close enough and the imperfections are needed anyway for oil so hand scraping is used for bearing surfaces.

Right. You start with any two plates and make them flat with respect to each other. One will be convex and one concave of course, then you take one of those and your third plate and make those two flat with each other, the switch out again using the third plate and the one not swaped out. Keep repeating until all three are flat with respect with each other - only true flat will have all three flat and the repititions keep getting closer.

of course if you have a known flat surface you can save effort by making the new plate flate to the known flat.

It has. The Moore Special Tool Company makes diamond turning lathes much like this one. But replicating that precision on your own is still an immense achievement.

As Dan Gelbart once said: "Building your own lathe is an admirable ambition. Building one with micron accuracy is a terrible illness which, at my age, has no cure."

New Scientist published a reminiscence of somebody in the relatively modern era doing the 3 plate dance. I wish I could find it online. They said it was tedious work.

Maudsleys 3 plates are in the London science museum along with Whitworths screw, and some of Marc Brunels stuff. Same room as the meccano differential analyser and the harmonic calculator for tide charts and Babbage bits.

Edit: found it - https://archive.is/iyCzB

It would be hard to make a human into a truly flat surface. I suppose if you have big enough granite blocks...

Not a machinist at all, but how can a lathe replicate parts which don’t have an axis of rotation?

Thank you so much!! I have been trying to find this book series for years. I I first heard about it on this or another forum ages ago, but couldn't remember enough specifics to find it.

Oh yeah smart guy? Well how do you make the granite?

Know a guy who bought a 2 trailers loads of lathes and assorted machine tools for less than 10k in the Rust Belt. Was even remanufacturing diesel engines

most lathes have a hole in the chuck to feed the work through. so if the material is ground down by hand to a diameter small enough to fit in the hole then to be turned and then removed and flipped over it's possible.

My pleasure!

I found a copy of Vol. 2 ages ago and gave it away, and was glad to be able to purchase the updated all-in-one leatherbound edition.

That said, there is a certain charm to the originals with their typewritten text and hand-inked illustrations.

I also was impressed at Chris Borge's lathe build:

https://www.youtube.com/watch?v=6Js8erWbsDQ

It's small and kind of underpowered, but not useless! The central idea is to 3D print shells that hold metal parts and are then filled with concrete for rigidity and mass. Quite clever, I think.

A lathe is the only machine you need. Those flat surfaces are easy to create with basic hand tools. (easy - but expect to spend a month if creating a flat surface is your full time job)

No, good thermal management with a chiller, active thermal compensation, and glass scales make um precision on that scale reasonable. 10-100x better? Sure, you’re getting into machines where the room to keep them happy is significantly more expensive that the machine…

While interesting he hasn't read the gingery books and has made several 'mistakes' that gingery tells you how todo better. Though there is plenty of fault to pick in the gingery designs they show a clear understanding of how to do things and the mistakes are compromises based on materials available not a failure to understand precision.

You might also like English and American Tool Builders by Joseph Wickham Roe, I picked up a copy from a free library and enjoyed it. I should probably skim it again, then set it free into the system for someone else to find.

https://www.gutenberg.org/ebooks/72046

Also Maxim Kachurovskiy: https://www.youtube.com/watch?v=lnFw8G95LGo

Someday when I have time, after I fix my little rowboat, and sew the clothes/bags I want, and fix the porch, and, and, and...

For now there's satisfaction watching others do some of the project I haven't made time for.

There's a playlist (xor a 5 minute summary video) of a guy going the Gingery route

https://www.youtube.com/playlist?list=PL9d6LkFNP1fGjdW2RxqSH...

It's a straight edge, not a bed, but this is a fun watch: https://www.youtube.com/watch?v=pq47yXFmj24

I recently saw another video about a high accuracy 3d positioning stage. The differences and similarities were very interesting. For instance, both used rigid rods with ball joints for accuracy, but wildly different encoders and testing methods.

https://youtu.be/MgQbPdiuUTw?si=5r0DVsxVT1owyKk6

Much the same process, in one less dimension. And it looks time consuming but I bet immensely satisfying.

> of course if you have a known flat surface you can save effort by making the new plate flate to the known flat.

All the effort!

one of the good things about granite flat references, is that they last for ages, so you can get them reasonably cheaply second hand, if you can find a second hand machine shop specialist.

Even if your second hand plate is no longer flat enough it is still close enough so there is very little effort needed to bring it back to flat. (machine shops often check them on a regular basis and bring them back to flat as needed)

A better link would have been:

https://mooretool.com/about-us/publications/

(the book is long out of print, and used copies are exorbitant, but maybe if enough folks express interest it will get a reprint)

> Milling machines are also just lathes

Mills are more limited than lathe - they don't have leadscrews, which are a necessity in the "build yourself" phase. You cannot make arbitrary threads with a milling machine. Thread milling gives some capability in this arena, but that's a CNC process.

It's pretty much whiplash vs software. In software you get access to the source code for a lot of SOTA industrial sofware in almost every field.

In mechanical engineering/machining/etc. you mostly only get access to educational materials simplified to only demonstrate the concepts... plus a scant few sacred tomes.

Thanks, seems to fit the theme!

One can make arbitrary threads (vertically) on a CNC using a single point cutter (limited by the height of the Z-axis/thickness of the stock which one can fit a tool over/into):

https://community.carbide3d.com/t/thread-milling-in-metal-on...

A manual lathe will often have a gearbox which allows cutting threads on it:

https://www.youtube.com/watch?v=E_KF3n3oo08

This guy is quite interesting, because he starts from scratch without reading or experience, so you end up with a really wonky machine, but it's wonky in unusual ways that really make you think. Like the sibling comment says, it's obvious he hasn't read the Gingery books. This sounds like I'm throwing shit, but I'm not - it's actually how I work a lot of the time. Making a mistake gives you a deeper understanding of the issue than you would typically get from doing things the right way. For example, he overheated the gravers while sharpening them, which made them soft, and now he gets to learn about annealing and temper. And indeed, in the comments, he gets:

>Just for future reference on making gravers, you were correct that you do not want to get the pre-hardened steel red hot or it will lose its heat treatment. However you have to go much further than that and not allow it to heat above the desired temper temperature. For instance if it was previously tempered to a straw (yellowish brown) color but then while grinding it the steel turns blue, that means you have reduced the temper to a lower hardness. So you need to keep the steel cool and never let the temperature go beyond the desired temper temperature. You can think of it this way, hardening the steel makes it as hard as it can get (but too brittle to be good for much), then tempering reduces the hardness but makes it stronger, and this effect continues the hotter you temper it.

n.b. this sort of thing is absolutely endemic in the world of 3D printing, which is why most videos are fairly useless to learn from, but the comments are invaluable.